1. Field of the Invention
The present disclosure pertains to systems and methods for determining the flow rate of pressurized gas generated by a respiratory device corresponding to zero subject flow rate, and in particular, determining the flow rate using cluster analysis techniques.
2. Description of the Related Art
Estimating leak flow in respiratory devices providing pressurized flow of breathable air to a subject is necessary to provide the proper pressure support and ventilation to the airway of the subject during the therapy. An accurate determination of leak allows respiratory devices to effectuate precise synchronous triggering of pressure support functions necessary for a therapy regime, to maintain user comfort, and well as accurately measure respiratory flow parameters of the subject such as tidal volumes and peak flows. As with any form of leak estimation, there are underlying assumptions. When those assumptions are not correct, errors can amount quickly resulting in inaccurate triggering and user discomfort.
Time-domain evaluation methods applied to measured gas parameter values such as flow rate parameter values determined from sensors employed in respiratory devices are typical methods for determining the flow rate corresponding to zero subject flow. Slope analysis is one such method, however is often frustrated by noise, both in the devices control and measurement modules of the device and due to the subjects themselves.